This invention relates to an ultraviolet-curing silicon-containing resin composition that can be used to fabricate dielectric films in semiconductor devices, to a method for curing said composition, and to a patterning method using said composition.
It is well known that hydroxyl groups directly bonded to silicon (silanol) can be easily condensed in the presence of acid or base to form siloxane bonds (Chemistry and Technology of Silicones, pp. 211-216).
One method for curing siloxane polymers employs an acid generator, that is, a compound that generates acid upon exposure to ultraviolet radiation ("UV acid generator"). Silanol condensation is catalyzed by the generated acid and the siloxane polymer undergoes curing as a result. Japanese Patent Application Laid Open Kokai or Unexamined! Number Hei 6-80879 80,879/1994! and Jpn. J. Appl. Phys., Vol. 32 (1993), pp. 6052-6058, teach the fabrication of silicate glass thin films using the combination of a UV acid generator and special siloxane.
Another technology recently under active investigation attempts to use a compound that generates a base upon exposure to UV radiation ("UV base generator"), to accelerate silanol condensation and thereby effect the curing reaction.
Japanese Patent Application Laid Open Kokai! Number Hei 6-148887 148,887/1994!), discloses the cure of a composition comprising poly(silsesquioxane) or poly(silsesquioxane) and tetraphenoxysilane. In the first example of JP'887 the sensitivity (D50=radiation dose at which 50% of the film remains after development) is 25 mJ/cm.sup.2 for the polysilsesquioxane curing reaction by a photogenerated amine compound and is 60 mJ/cm.sup.2 even when the tetrafunctional silane monomer has been added to the system (all values measured at 254 nm).
Japanese Patent Application Laid Open Kokai! Number Hei 6-273936 273,936/1994!) discloses a curable composition comprising siloxane polymer and a base generator. JP'936 does not report sensitivity (D50) values, but does report 100 to 300 mJ/cm.sup.2 (365 nm) as the dose required for curing.
Japanese Patent Application Laid Open Kokai! Number Hei 6-148895 148,895/1994!) discloses the use of alkali-soluble siloxane polymer and a photobase generator. JP'895 reports a cure catalyzed by the organic amine generated by the decomposition of organic carbamate by from 600 to 1,500 mJ/cm.sup.2 UV radiation (365 nm).
Cured regions in which crosslinking has been induced by the above-described methods as a general rule have a substantially lower solvent solubility than the uncured regions, and the exploitation of this feature makes imaging possible.
The methods for curing siloxane polymer using a UV base generator can suffer from the following problems:
(1) long UV exposure times can be required due to a low sensitivity by the photobase generator; PA1 (2) the low catalytic activity of the generated base in the curing reaction can lead to a very poor cure in many silanol-functional silicone resins, or, when this is not the case, a lengthy post-bake at high temperatures can be required.
It is therefore an object of the instant invention to provide a UV-curable composition that can be cured by low-strength UV radiation while using mild post-bake conditions.
It is further an object of the instant invention to provide a method for curing the said composition and a patterning method that uses said composition.